Feed-governing means for arc lamps



Sept. 18, 1928. 1,684,817

P. R. BASSETT FEED GOVERNING MEANS FOR ARC LAMPS Filed Oct. 25. 1920 3 Sheets-Sheet 1 8 vwewlioz Sept. 18, 1928.

P. R. BASSETT FEED GOVERNING MEANS FOR ARC LAMPS Filed Oct- 25- 1920 a Sheets-Sheet 2 Snow W01, PRESTON REV-755E772 Sept. 18, 1928. 1,684,817

P. R. BASSETT FEED GOVERNING MEANS FOR ARC LAMPS Filed Oct. 25- 1920 s sheds-sheet 3 I I I 5] v1 vow box PRES m/v Kill/155577. 0 t3 Z1 d/CIHQWM Patented Sept. 18, 1928.

UNITED STATES, PATENT OFFICE.

PRESTON R. BASSETT, OF BROOKLYN, NEW YORK, ASSIGNOR TO THE SPERRY GYBO- BCOPE COMPANY, 01 BROOKL YN, NEW YORK, A CORPORATION OF NEW YORK.

IEED-GOVER'NRIG MEANS FOR ARC LAMPS Application filed-October 25, 1920. Serial No. 419,228.

This invention relates to are lamps and has for its chief object the provision of highly sensitive and accurate means of simple construction for maintaining constant the length 5 of the arc. Heretofore it has been the practice to control the arc length by means of variations in the current through or voltage across the are. To this end it has been common to provide an electromagnet either in series or in parallel with the arc and adapted upon a suflicient change in the current through such magnet resulting from change in the arc length to bring into action certain electrode feeding means to restore the are to its proper length. In order for such systems to be sensitive to small changes in the arc length it is necessary that the magnet be of comparatively large size so that a small change in the current will cause the magnet to bring the feeding means into action. According to my invention, however, the action of the electrode feeding means is independent of variations in the voltage across or cur rent through the arc, and instead such means is brought into operation in response to changes in either the position or size, or both position and size of the arc flame. My invention is especially adapted for the control of high intensity and other flaming arclamps having. a well defined and definitely positioned tail flame. In my system of control the electrode feeding means comes into action in response to changes in the arc length much smaller than in prior systems, and fur thermore the current through the magnet which controls said feeding means may change from zero to a considerable amount upon a very slight change in the arc length, so that a much smaller control magnet may be employed.

Another object of my invention is to provide controlling means for are lamps comprising conductors on opposite sides of the a :c flame whereby movement of the arc flame in one direction results in a flow of current through one conductor and causes the negativc electrode to be fed toward the positive to maintain the arc length constant and movement of said flame in another direction causes a flow of current through the other conductor and the "feeding of the positive electrode so that its crater is maintained in a definite position. By this means the arc flame is trapped, soto speak. between said conductors so that movement of the flame in lamp mechanism of Fig. 1.

one direction or the other causes feeding of either the positive or the negative electrode, w1th the result that the flame is maintained in a definite position and at the same time the arc length is kept constant and the positive crater held in a given position.

A further. object of my invention is the provision of an improved type of conductmg member positionable adjacent the are flame, which member is so constructed as to readily dispose of the heat received from the arc, and which may be adjustable so as to present different portions of this area in proximity to the arc flame.

Other objects and advantages of my invention will become apparent as the description thereof is hereinafter developed.

Referring to the drawings wherein I have shown what I now consider to be the preferred forms of my invention:

Fig. 1 is a side elevation of one form of automatically controlled arc lamp mechanism embodying my invention, said mechanism being removed from its supporting housing.

Fig. 2 is a vertical sectional view of a housing for the lamp mechanism of Fig. 1, the position of the arc flame and certain parts of the lamp mechanism of Fig. 1 being shown in dotted lines.

Fig. 3 is an end elevation, partly in section, of the lamp housing of Fig. 2, certain parts of the latter figure being omitted.

Fig. 4 is an enlarged end elevation of the Fig. 5 is a diagrammatic view illustrating certain variations in the position of the arc flame inresponse to changes in the position of the negative electrode.

Fig. 6 is a wiring diagram. Fig. 7 is a side elevation of amodified form of automatically controlled arc lamp mechanism.

Figs. 8 and 9 are detail views of certain parts of Fig. 7.

I have shown my invention as applied to an arc lamp especially adapted for motion picture projection. In Figs. 2 and 3 I have shown one form of housing for the lamp mechanism. This housing, as shown, is com- 5 posed of an outer shell 2 and an inner shell 3 suitably connected thereto as by bolts 4 passing through flanges at the rear ends of said outer shell, one of which flanges is shown at 2 in Fig. 3. Suitably held in position ad- 110 jacent the front portion of housing section 3 are frames 5 WhlCh carry the condensers or lenses 6 for focusing the flood of light through the projecting tube 7 into the picture operatin mechanism, which mechanism is not shown erein as it forms no part of the present invention. An opa ue plate or shutter 8 is connected at one si e to a rod 9 rotatably j ournaled in a bearin 10 in the front wall of housing section 3. The rod 9 extends forwardly of the exterior of housin section 2, as shown in dotted lines, where said rod is rovided' with a handle 11. It will be seen em this construction that by turning rod 9 in one direction or the other the shutter 8 may be moved into or away from a position in which it prevents the light of the are from reaching the lenses 6. Suitable ledges, one of i which is shown at 12, are provided within housing section 3 for receiving the base plate 13 of the lamp mechanism, from the bottom of which base plate are suspended the motor 14 and housing 15 for a fan 16 driven by said motor. The housing 15 is, of course, open at its ends so that air may be drawn through said housing when fan 16 is rotated. Below the housing section 3 is an extension 17 open at its rear end and adapted to receive the fan housing 15. The forward part of extension 17 is provided with an incline 18, so that as the fan draws air through the rear opening of said extension the said incline 18 assists or guides the current of air upwardly. The fan 16 thus furnishes air to cool the condensers 6 as well as the lamp mechanism with in housing section 3. Inclined vanes 19 at the top of the housing section 3 form outlets for the air forced into said housing section as well as for the fumes or products of combustion from the lamp. The said air and fumes may finally escape from the outer housing section 2 through the opening in the rear end thereof or through exhaust passages 20. The outer housing section 2 is also open at the bottom thereof so that air may be drawn upwardly between sections 2 and 3.

Doors 21 and 22 may be provided for placing and removing the lamp mechanism within the housing. As shown in connection with door 21 in Fig. 3, said doors are each formed of spaced walls suitably connected together and serving to close corresponding openings in sections 2 and 3.

A bafile plate 23 may be suspended from the upper portion of housing section 2 to prevent the top of said section from becoming too hot.

While my system of control may be a plied to any of a wide yariety of lamp. mec anisms, I have shown by way of example, in Figs. 1 and 4, one form of mechanism with which my invention may be used. Secured to the upper face of base plate 13 are upwardly extending brackets 24, 25, suitably insulated from said plate. To the tops of said braces above described mechanism is and slidable on said rod 29. Said gear meshes with a gear fixed on an electrode holder 36 rotatably carried by carriage 31. .The positive electrode 37 may be gripped by said holder adjacent its rear end and may project through a guide 38 adjacent its burning end. Fixed on rods 29 and 30 are ratchet wheels 39 and 40, respectively.

Positioned to the rear of and below the a reciprocating member 41 to which is secured a plurality of pawls 42, 43, and 44. Pawls 42 and 43 operate ratchet wheel 39 on both reciprocations of bar 41, while pawl 44 is normally disengaged from ratchet wheel and is thrown into engagement therewith only when electromagnet 45 is energized, which occurs only when the positive electrode is to be fed forward as will ap ear hereinafter. that it bar 41 is constantly reciprocated ratchet 39 and gears 34 and 35 will be constantly rotated so that a continuous rotation is imparted to the positive electrode 37. At the same time, when pawl 44 is thrown by energization of magnet 45 into engagement with ratchet wheel 40 threaded rod 30 is rotated to advance the carriage 31 and electrode 37.

For imparting a continuous reciprocation to bar 41 the shaft 46 of motor 14 may be provided at its outer end with a worm 46 and may extend within a housing 47 within which housing the said worm engages a worm wheel 48 on the same shaft as a crank disc 49. The said crank disc is connected with bar 41 by a pitman 50. Consequently if motor 14 runs continuously during the operation of the lamp, bar 41 will be continuously reciprocated. The mechanism thus far described for feeding and rotating the positive electrode is disclosed in great detail in the application of Theodore Hall, Serial No. 377,743, filed April 30, 1920, for projector lamps.

Extending forwardly from the bracket 25 is an arm 51 which is insulated from said bracket at 52 and carries a guide rod 53 on which the carriage 54 is slidably mounted. Said carriage is in threaded engagement, as shown, with the rod 55, which rod is rotatably carried by arm 51. The rear end of the negative electrode 56 is gripped by the carriage 54 while the forward end protrudes through a guide 57. Rod may be provided with an elongated pinion 58 meshing with a gear 59 on the same shaft as bevel gear 60 which in turn meshes with bevel gear 61 on shaft 62.

It will now be seen tached to the armature 67 of an electromagnet 68. It will thus be seen that when said magnet 68 is energized pawl 65 will be moved into engagement with ratchet 64, and as a result shaft 62 will be rotated and the negative electrode 56 fed toward the positive electrode 37.

To effect a rapid striking of the arc rod 55 may have long bearing portions 69 to permit longitudinal sliding of said rod in its bearings 70, while the lower end 71 of said rod may constitute the core of a solenoid 72 fixed to the lamp. A spring 74 engaging a stop 75 at a one end and at the other a plate 76 against which core 71 bears rotatably, normally presses rod55 upwardly to maintain electrode 56 in contact with electrode 37. Solenoid 72 may be in series with the are so as to be energized throughout the period that the current is flowing. Assuming that the electrodes 37 and 56 are in engagement, it will be evident that as soon as the current is turned on core 71 will be attracted by solenoid 72 to draw rod 55, carriage 54, and electrode 56 downwardly to the position shown in Fig. 1, thus striking the arc.

The feeding of the positive electrode is preferably controlled by means responsive to the position of the positive crater and to this end a third electrode 77 operating on the principle more fully disclosed in my application filed October 15, 1918, Serial No. 258,255, Means for focusing searchlights may be provided. Said third electrode is shown in Fig. 1 as a metal bar supported by and insulated from extension 27 of plate 26 and extending to a position adjacent the arc flame. As shown in Fig. 6 said electrode 77 is electrically connected to magnet 45, the latter being connected to the main 79. WVhen the positive crater burns away from the predetermined position the are flame approaches the third electrode and sufficient current flows from electrode 56 and the are: flame through the. thirdelectrode and magnet 45 to cause the pawl 44 to engage ratchet 40, whereupon the positive electrode is fed forward and magnet 45 deenergized. Pawl 44, which is resilient and normally biased to its position shown in Fig. 4 wherein it is out of engagement with said ratchet 40, thereupon moves out of engagement with said ratchet and the feeding of the positive electrode ceases. The armature- 14" and field 14" of motor 14 may be connected'across mains 78, 79, as shown.

As disclosed in the application of Theodore Hall, Serial No. 377,743, previously referred to, knobs 80, 81, 82, and 83 slidably mounted in the rear end of the lamp housing may be provided for hand manipulation of the electrodes and lamp mechanism when desired. Knob 80 is provided at its forward end with a hollow sleeve 80 carrying a pin 80", which pin, when said knob is pushed forwardly, is adapted to engage in a slot 29 in the rear end of rod 29 so that the ositive electrode may be turned independent y by hand should the same be desired for any purpose. Similarly knob 81 may be pushed forwardly to turn feed rod 30 to adjust the positive electrode, while knob 82 is for a like purpose for adjusting the position of the negative electrode. Knob 83 may be threaded through a bushing 85 and may be connected rotatably at its forward end to a sleeve 86 in turn connected by a pin 84 to base plate 13, so that the base plate and entire lamp mechanism carried therebymay be adjustably positioned in the housing by turning knob 83. The knobs 80, 81, and 82 may be mounted in a suitable door 87 affording access to the rear of the lamp mechanism. An aperture 88 in the rear of housing section 3 may be provided just above door 87 for inserting a new positive carbon whenever desired and may be closed normally by pivoted shutter 89 shown in Fig. 3.

For controlling the feeding of the negative electrode to maintain constant the length of the are I have shown a fourth electrode 90 adjacent the are flame and in circuit with the electromagnet 68. The said fourth electrode should be so located that at least a portion thereof lies in the path of movement of the are flame as the negative electrode burns -away.. Of course, the fourth electrode may be of any of a wide variety of shapes and may be supported in any of a great number of positions. By way of example in Figs. 1 and 4 I have shown the fourth electrode as a ring 90 supported by the upward extension 27 of plate 26, said electrode being insulated from the third electrode and from said extension. As shown, a bracket 91 may be secured to said extension 27 and a single bolt 92 may serve to secure the fourth electrode 90, third electrode 77, and interposed insulating washers 93 to bracket 91. The bolt 92 is shown insulated from bracket 91 and third elect-rode 77 and may serve to conduct current to fourth electrode 96. The third electrode 7 7 may be provided with a suitable binding post 94.

As shown the electrode 90 is dish shaped and its periphery is preferably inclined so that only an edge of said electrode is nearest the are flame. Preferably the part of the inner periphery of the fourth electrode that lies opposite the positive crater is inclined along a line passing through the center of the crater. In this way the minimum portion of the said fourth electrode is exposed to the intense heat of the arc. By making the fourth electrode in the shape of a ring a large radiat ing surface is provlded for cooling said electrode.

The type of are to which my invent-ion has especial adaptation is illustrated in Fig. 5. These arcs are one of the recent developments and are more fully described in my Patent No. 1,328,311 for method of operating flaming arc lights for projectors dated Jan. 20, 1920 and in my copending application Ser. No. 391,973 filed June 26, 1920 for concentrated flaming arc lamp for projectors and are characterized by a unidirectional and well defined tail flame or plume. Insuch arcs and similar arcs which are burned at very short are lengths the position, shape and size of the tail flame 200 all change to a very marked degree on minute changes in are length.

In fact, a given change in the position of the tip of the negative electrode results in a change three or four times as great in the position of the arc flame. Consequently, the control of the means for feeding the negative electrode to maintain the arc length constant may be made extremely sensitive. The scale of Fig. 5 showing different changes in the position of the negative electrode and in the height and position of the arc flame is somewhat enlarged for the sake of clearness. Assuming that position A is the correct position of the tipof the negative electrode when the arc is of the proper length and that A is the corresponding position of the arc flame, a slight change in the position of the negative electrode from A to B will result in an increase in height and alteration in position of the arc flame from A to B. In the latter position the arc flame is just out of contact with fourth electrode 90. Further movement of the negative electrode away from the positive increases the height ofthe arc flame still further and also brings the are flame into contact or very near with the fourth electrode. Thus a movement of the negative electrode from position B to C would result in further increase in the height of the flame and in movement of the edge of the are flame on the'side of the negative electrode from B to C, as shown. Since the burning away of the negative electrode causes not onlv the side of the flame adjacent said electrode to move but also causes the height of said flame to increase, it is evident that the fourth electrode may be so positioned with respect to the are flame as to be touched by the latter either when the height of the flame becomes sufiiciently increased or when the side of said flame adjacent the negative electrode moves a sufficient distance away from the positive, or in response to a change both in the height of the flame and'in the position of the side of t the flame adjacent said negative electrode.

During the changes in height and position of the arc flame above discussed, it should be noted from Fig. 5 that the position of the edge of the are flame adjacent the third elec-.

trode 77 remains practically unchan (1, so that the operation of the means for eeding the positive electrode to hold the crater of the latter in its predetermined position is undisturbed, and said means will be brought into action in the usual way by the departure of said crater from said position. I

The fourth electrode is shown in Fig. 6 as electrically connected with ma net 68, the latter being connected with main 9. It will thus be seen that when the are flame touches the fourth electrode current will flow from main 78 to the negative electrode where part of the current goes on through the arc and positive electrode to the main 79 and the other part goes through the arc flame, fourth electrode 90, and magnet 68, to said main 79. Armature 6731's thereby attracted and pawl drawn into engagement with ratchet 64. The negative electrode is thus fed toward the positive. Upon the withdrawal ofthe arc flame from contact with the fourth electrode, magnet 68 is deenerg'ized and pawl 65, which is resilient and normally biased, to its position out of engagement with ratchet 64, withdraws from engagement with said ratchet and the feeding of the negative electrode ceases. It will be evident that it is not necessary for the arc flame. to actually touch either the third or fourth electrode in order to cause operation of the corresponding feeding means, since, as explained in my application N 0. 258,255 previously referred to, the gas surrounding the are is conducting to some extent and the value of such gas as a conductor varies inversely with the distance from the arc flame. Consequently, as the arc flame approaches either electrode 77 or 90 the current through the corresponding magnet may increase sufficiently to cause operation of the feeding means before the flame actually touches said electrode. The design of magnets 45 and 68 and associated parts may, of course, be varied to bring the feeding means into operation either before or at the time that the arc flame touches the corresponding electrode.

The operation of my control systemwill be readily apparent from the'foregoing description. It will be seen that the means for feeding the negative electrode to maintain the length of the are substantially constant is independent of variations in-the current through or voltage across the are and is controlled solely by variations .in the position of the arc ame resulting from changes in the length of the are. Since the current through magnet 68 may vary from zero when time, since a small change in the position of the ne ative electrode results in a much larger dhange in the position of the arc flame, the control of the feeding means for said tnegative electrode is rendered highly sensi ive.

Since movement of the arc flame in one direction away from its proper position causes feeding of the positive electrode and movement of said flame in the opposite direction causes feeding of the negative electrode, it

will be seen that the flame is trapped, so to s eak, between the third and fourth electro es and that the arc length is thereby maintained constant and the positive crater held in a iven position.

In Fig.% I have shown a somewhat modi fied form of lamp mechanism and also certain modifications in the third and fourth electrodes. Parts in Fig. 7 correspondin with parts of Figs. 1 and 4 are designated y the same numerals with a prime added. The main points of difference between the lamp mechanism of Fig. 7 and that of Figs. 1 and 4 are in the means for striking the are and in the angle at which the negative electrode is positioned with respect to the positive. In Fig. 7 the negative electrode is shown at a much greater angle with respect to the positive.

As shown, the arm 51 which carries the negative electrode 56 is pivoted at 96 to an extension'97 secured to and insulated from the bracket 25'. A spring 98 coiled about pivot 96 and hearing at one end against a pin 99 on bracket 25 and at its other against a pin 100 on arm 51' tends to maintain electrode 56 in engagement with the positive electrode 37'. In this position the edge 101 of arm 51 may contact with the edge 102 of a projecting portion 110 of extension 97, said projecting portion thereby forming a stop. A link 103 serves to connect arm 51' with the pivoted armature 104 of an electromagnet 7 2' supported by and insulated from plate 26.

Said magnet 7 2 is in series with electrodes a 37 and 56' and when said electrodes are in contact and the current is turned on said magnet is energized and attracts its armature thereby separating electrode 56 from electrode 37 and moving arm 51 to its position shown in Fig. 7 wherein edge 105 of said arm engages edge 106 of the stop or projection 110 on extension 97. The are is thereby struck.

In order to permit the striking of the arc in the manner aforesaid the shaft 62, may be constructed substantially as shown in Figs. 7 and 9. The forward portion 62 of shaft 62' may be pinned or otherwise attached to an insulating sleeve 107 surrounded by and attached to a metal sleeve 108 Within sleeve 107 is a keyway 109 within which fits a suitable key member 111 on a shaft 112 which carries at its other end a forked member 113 pivot/ed by pins 114 to a ball Or block 115 held within said forks. Pivoted to said ball on a line at right angles to the line of pins 114 is a forked member 116 secured to the other portion of shaft 62". In this manner a universal connection is provided between the rear part of shaft 62' and the part 112 thereof and relative slidin is permitted between the said part 112 an the forward portion 62", so that the pivotal movement of arm 51 will not be prevented by said shaft 62, and at the same time 10 tation of said shaft will result in rotation of gear 61' to feed the negativeelectrode toward the positive.

The third electrode 77' is shown in the form of a flat riigg whereby a large radiatin surface is secur It should also be note that said ring is inclined so that only a poi.- tion of the upper edge thereof is nearest the arc flame, and a minimum portion of said electrode is thereb exposed to the intense heat of the arc. aid ring 77 ma be adjust-ably held" between suitable c amping members 117 and 118 earriedby extension 91' of bracket 27'. The member 117 may be provided with a projection 117' passing throu h member 118 and the extension 91 and tireaded to receive a nut' 119 beneath said extension 91 to clamp ring 77 firmly between members 117 and 118. Suitable insulating washers 120 may be interposed between member 118 and extension 91' and between nut 119 and said extension. By unscrewin nut 119 it will readily be seen that ring 77 may be shifted to present another portion. of its area adjacent the arc flame, and in this manner the period of usefulness of the third electrode may be greatly prolonged.

The fourth electrode 90, instead of being dish-shaped like electrode 90, is shown in the form of a cylinder which is mounted in a forked clampin member 121 secured to and insulated from racket 27 A screw 122 may serve to clamp the fourth electrode adjustbl within the said forked member, so that different portions of said fourth electrode may be presented adjacent the are flame. As shown, the entire cylindrical electrode 90' is inclined so that its portion in front of the positive crater lies along a line passing throu h the center of said crater, and thus the minimum portion of said electrode is exposed to the heat of the are. a

In accordance with the provisions of the patent statutes, I have herein described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other means. Also, while it is designed to use the various features and elements in the combination and relations described, some of these may be altered and others omitted without interfering with the more general results outlined, and the invention extends to such use.

Having described my invention, what I claim and desire to secure by Letters Patent is: c

1. In an arc lamp, a pair of electrode holdore for the electrodes, means including a member adjacent the are flame and responsive to a predetermined position thereof for feeding one of said electrodes, and means'in eluding another member adjacent the arc flame and responsive to another thereof for feeding the other of sald electrodes.-

2. In a flamin arc lamp employing a pair of electrodes adapted to produce an arc, means responsive to 'movement of the arc flame in one direction for feeding one of said electrodes, and means responsive to movement of said flame in another direction for feeding another of said electrodes.

3. In an arc lamp the combination with a pair of electrode holders, of means for feeding an electrode through one of said holders, means for feedin an electrode through another of said hol ers, and means responsive to the position of the arc flame for controlling each of said feeding means independent 1y of the other. e

4. In a flaming arc lamp, the combination with a pair of electrode holders, of means for feeding an electrode through one of said holders, means for feeding an electrode through another of said holders, means responsive to the position of the arc flame in one direction for controlling one of said feed- 7 ing means, and means responsive to the position of the arc flame in another direction for controlling the other of said feedin means.

5. In a flaming arc lamp, the com ination with a pair of electrode holders, of means for feeding an electrode through one of said ositionholders, means for feeding an electrode through the other of said holders, and means means.

6. In an arc lamp, the combination with a pair of electrode holders, of means for feeding an electrode through one of said holders,

means for feeding an electrode throu h another of said holders, an electrical con uctor adjacent the are, means including an electromagnet in circuit with said conductor for bringing one of said feeding means into action, a second electrical conductor adjacentthe are on the opposite side thereof from said first mentioned conductor, and means connected with said second conductor for bringing the other feeding means into action.

7. In a feeding mechanism for flaming projector lamps, the combination with positive and negative holders, of feeding mechanism for each electrode, means located adjacent the positive holder and responsive to the proximity of the arc flame for governing the positive electrode feeding mechanism, and means located at a greater distance from said positive holder and also responsive to the proximity of the arc flame for governing the negative electrode feeding mechanism.

8. In an arc lamp, the combination with a pair of electrode holders, of means for feeding an electrode through one of said holders, means for feeding an electrode through another of said holders, means responsive to the position of the arc flame in a given direction for feeding an electrode through one of said holders, and means responsive to the. size of the arc flame for feeding an electrode through the other of said holders.

In testimony whereof I have aflixed my signature. 4

. PRESTON R. BASSETT 

